The present invention relates to an image signal binary encoder for converting analog image signals into binary output signals.
Conventionally, in the case where contents of an original document are converted into image signals of two gradations, it has been a general practice that in order to rapidly perform arithmetic operation for calculating an average density of a predetermined area, a number of adders are operated concurrently so as to obtain a sum of respective digital density data of sections of the predetermined area and then, the average density is obtained by dividing the sum by the number of the sections.
However, this known arithmetic operation method has such a drawback that the number of the adders is required to be increased further as the number of the digital density data of the predetermined area becomes larger.